U.S. patent number 10,823,819 [Application Number 16/080,504] was granted by the patent office on 2020-11-03 for radar system including an antenna array for transmitting and receiving electromagnetic radiation.
This patent grant is currently assigned to Robert Bosch GmbH. The grantee listed for this patent is Robert Bosch GmbH. Invention is credited to Benedikt Loesch, Michael Schoor.
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United States Patent |
10,823,819 |
Loesch , et al. |
November 3, 2020 |
Radar system including an antenna array for transmitting and
receiving electromagnetic radiation
Abstract
A radar system includes an antenna array for sending and
receiving electromagnetic radiation, the array including N
transmitting antennas and M receiving antennas, objects being
detectable within the detection area of the antennas according to
the MIMO principle using the antennas. The transmitting antennas
transmit signals that are orthogonal to one another during a
transmission cycle. N-n of the transmitting antennas are situated
horizontally next to one another and n of the transmitting antennas
are situated in a horizontally offset manner at an identical offset
from respective ones of the N-n transmitting antennas. M-m of the
receiving antennas are situated horizontally next to one another
and m of the receiving antennas are situated vertically offset from
the M-m receiving antennas.
Inventors: |
Loesch; Benedikt (Stuttgart,
DE), Schoor; Michael (Stuttgart, DE) |
Applicant: |
Name |
City |
State |
Country |
Type |
Robert Bosch GmbH |
Stuttgart |
N/A |
DE |
|
|
Assignee: |
Robert Bosch GmbH (Stuttgart,
DE)
|
Family
ID: |
1000005157031 |
Appl.
No.: |
16/080,504 |
Filed: |
December 29, 2016 |
PCT
Filed: |
December 29, 2016 |
PCT No.: |
PCT/EP2016/082808 |
371(c)(1),(2),(4) Date: |
August 28, 2018 |
PCT
Pub. No.: |
WO2017/148561 |
PCT
Pub. Date: |
September 08, 2017 |
Prior Publication Data
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|
|
|
Document
Identifier |
Publication Date |
|
US 20190011532 A1 |
Jan 10, 2019 |
|
Foreign Application Priority Data
|
|
|
|
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Feb 29, 2016 [DE] |
|
|
10 2016 203 160 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01Q
1/3233 (20130101); G01S 13/931 (20130101); G01S
13/42 (20130101); G01S 7/032 (20130101); H01Q
21/065 (20130101) |
Current International
Class: |
G01S
7/03 (20060101); H01Q 1/32 (20060101); G01S
13/931 (20200101); G01S 13/42 (20060101); H01Q
21/06 (20060101); G01S 13/00 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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102009032114 |
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Jan 2010 |
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DE |
|
102014201026 |
|
Jul 2015 |
|
DE |
|
2963442 |
|
Jan 2016 |
|
EP |
|
H05218736 |
|
Aug 1993 |
|
JP |
|
2003248055 |
|
Sep 2003 |
|
JP |
|
2014062779 |
|
Apr 2014 |
|
JP |
|
Other References
International Search Report dated Mar. 27, 2017 of the
corresponding International Application PCT/EP2016/082808 filed
Dec. 29, 2016. cited by applicant.
|
Primary Examiner: Gregory; Bernarr E
Attorney, Agent or Firm: Norton Rose Fulbright US LLP
Messina; Gerard
Claims
What is claimed is:
1. A radar apparatus, comprising: a radar system, including: an
antenna array for sending and receiving electromagnetic radiation;
N transmitting antennas; and M receiving antennas; wherein the
radar system is configured to use the transmitting and receiving
antennas to detect objects within a detection area of the
transmitting and receiving antennas in a Multiple Input Multiple
Output (MIMO) manner; wherein the N transmitting antennas are
configured to transmit signals, wherein each of the transmitted
signals are orthogonal to one another during a transmission cycle;
wherein N-n of the N transmitting antennas are situated
horizontally next to one another; wherein n of the N transmitting
antennas are situated at an identical horizontal offset from the
N-n transmitting antennas; wherein M-m of the M receiving antennas
are situated horizontally next to one another; and wherein m of the
M receiving antennas are situated vertically offset from the M-m
receiving antennas.
2. The radar system of claim 1, wherein n=1.
3. The radar system of claim 1, wherein m=1.
4. The radar system of claim 1, wherein the m receiving antennas
each has a different vertical offset from the M-m receiving
antennas.
5. The radar system of claim 1, wherein N=3.
6. The radar system of claim 1, wherein N=4.
7. The radar system of claim 1, wherein M is a multiple of 3.
8. The radar system of claim 1, wherein the transmitting antennas
are patch antennas, the receiving antennas are patch antennas, or
both the transmitting antennas and the receiving antennas are patch
antennas.
9. The radar system of claim 1, wherein all M receiving antennas
are patch antennas that includes a same number and array of
patches.
10. The radar system of claim 9, wherein the transmitted signals,
which are orthogonal to one another, are implemented using time
division multiplexing, code division multiplexing, or frequency
division multiplexing.
11. The radar system of claim 1, further comprising: a monolithic
microwave integrated circuit (MMIC) situated centrally between the
N transmitting antennas and M receiving antennas.
12. The radar system of claim 11, wherein the monolithic microwave
integrated circuit (MMIC) includes a signal processor for
transmitting channels and receiving channels.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
The present application is the national stage of International Pat.
App. No. PCT/EP2016/082808 filed Dec. 29, 2016, and claims priority
under 35 U.S.C. .sctn. 119 to DE 10 2016 203 160.0, filed in the
Federal Republic of Germany on Feb. 29, 2016, the content of each
of which are incorporated herein by reference in their
entireties.
FIELD OF THE INVENTION
The present invention relates to a radar system including an
antenna array for sending and receiving electromagnetic radiation
for object detection according to the MIMO principle.
BACKGROUND
In the automotive industry, adaptive cruise controls, which allow
for a cruise control in the sense of a distance control and make
driving in a convoy of cars more comfortable, have been
increasingly used in recent years. Here, radar sensors are used in
most cases which include antenna arrays for detecting preceding
objects and other surroundings objects.
An adaptive cruise control of this type is, for example, known in
the publication "Adaptive Fahrgeschwindigkeitsregelung ACC,"
published in April 2002 by Robert Bosch GmbH, Stuttgart, Germany,
having the ISBN number ISBN-3-7782-2034-9.
An antenna array is known from DE 10 2009 032 114 A1, for example,
where a radar system for detecting the surroundings of a motor
vehicle, including means for detecting reflection points, which can
be driven over or under, is illustrated and which includes patch
antennas for transmitting and receiving electromagnetic
radiation.
SUMMARY
According to example embodiments of the present invention, a radar
system includes an antenna array for sending and receiving
electromagnetic radiation, N first antennas being provided for
transmitting and M second antennas being provided for receiving and
objects being detected within the detection area of the antennas
according to the MIMO principle using the N first transmitting
antennas and the M second receiving antennas. The N first
transmitting antennas transmit transmitted signals, which are
orthogonal to one another, during a transmission cycle; N-n of the
N first transmitting antennas are situated horizontally next to one
another; n of the N first transmitting antennas are situated in a
vertically offset manner at an identical offset in each case in
relation to the N-n transmitting antennas which are situated
horizontally next to one another; M-m of the M second receiving
antennas are situated horizontally next to one another; and m of
the M second receiving antennas are situated in a vertically offset
manner in relation to the M-m receiving antennas which are situated
horizontally next to one another.
A principle of the present invention is to provide a radar system
including an antenna array which makes it possible to achieve,
together with MIMO time division multiplexing, a good azimuth
estimation as well as, across the relevant angle range, an
unambiguous elevation angle estimation having a large aperture,
i.e., a high degree of accuracy and a high degree of separability.
At the same time, structures are made possible with the aid of the
array of antennas according to the present invention so that the
high-frequency chip which contains the transceiver components and
can be designed as an MIMIC (monolithic microwave integrated
circuit), can be placed centrally within the sensor, thus resulting
in short and approximately equally long feed lines to the antennas.
This is advantageous with regard to attenuation losses and phase
synchronization between the individual high-frequency channels.
It can be advantageously provided that the n transmitting antennas,
which are situated in an offset manner in relation to the N-n
transmitting antennas situated horizontally next to one another, is
exactly one transmitting antenna. In the case of this
implementation, in which n=1, all other transmitting antennas are
situated horizontally next to one another with only one antenna
being vertically shifted. This allows for a precise ascertainment
of the azimuth which is of particular importance for a distance
control in motor vehicles. While the ascertainment of an elevation
angle is made possible, the azimuth is ascertained more precisely
than the elevation angle during the measurement of this azimuth,
since the latter is of greater importance for driving tasks of an
adaptive cruise control system.
It is furthermore advantageous that the m receiving antennas, which
are situated in an offset manner in relation to the M-m receiving
antennas situated horizontally next to one another, is exactly one
receiving antenna. In this advantageous embodiment in which m=1,
the receiving antennas are situated horizontally next to one
another, thus allowing for a precise ascertainment of the azimuth
of the detected objects as well as for an elevation angle
estimation of the received signals at the same time. In this case,
while the ascertainment of an elevation angle is also made
possible, the measurement of the azimuth is more precise than the
measurement of the elevation angle, since the former is of greater
importance for driving tasks of an adaptive cruise control
system.
It is furthermore advantageous that the m receiving antennas, which
are situated in an offset manner in relation to the M-m receiving
antennas situated horizontally next to one another, each has a
different vertical offset in relation to the M-m receiving antennas
situated horizontally next to one another. As a result of the
different vertical offsets of the individual antennas, it is
possible to carry out measurements having different apertures and
different resolution capacities of the received signals. In the
case of an identical unambiguity range, the implementable aperture
having different vertical offsets is in addition greater than when
equal vertical offsets are used (uniform linear array).
It is furthermore advantageous that the N transmitting antennas
and/or the M receiving antennas are designed as patch antennas.
Patch antennas are rectangular antenna fields which can be etched
out of the copper layer of a circuit board. This makes it possible
to form complicated antenna arrays by structuring and etching away
a copper layer, without the manufacturing process requiring more
effort when the complexity of the structures increases. Patch
antennas of this type are manufacturable particularly
cost-effectively and easily.
It is furthermore advantageous that all M receiving antennas
include the same number and the same array of patches. As a result
of this feature, the entire antenna array is made up of multiple
identical patch antennas.
It is furthermore advantageous that the transmitted signals, which
are orthogonal to one another, are implemented using time division
multiplexing, code division multiplexing, or frequency division
multiplexing. For transmitting orthogonal transmitted signals,
signals that do not interfere with one another are to be generated,
which makes the listed methods of time division multiplexing, code
division multiplexing, or frequency division multiplexing,
particularly suitable.
It is furthermore advantageous that a monolithic microwave
integrated circuit (MIMIC) is situated centrally between the N
transmitting antennas and M receiving antennas. It is thus made
possible that the feed lines from the monolithic microwave
integrated circuit to the antenna ports can be designed to have
approximately the same length, whereby approximately the same phase
relations result between the individual transmitted signals or
between the individual received signals and the feed lines can be
kept preferably short at the same time, so that attenuation of the
transmitted signals can be minimized at the same time.
It is furthermore advantageous that the monolithic microwave
integrated circuit (MMIC) includes signal processing devices for
transmitting channels as well as signal processing devices for
receiving channels. It is thus made possible to manufacture a
particularly small antenna which can in addition be manufactured
cost-effectively, since a better part of the circuit parts of the
radar system is co-integrated into the monolithic microwave
integrated circuit and, outside of this IC, only the antenna
structures must be provided on a circuit board.
Other features, possible applications, and advantages of the
present invention are derived from the following description of
exemplary embodiments of the present invention, which are
illustrated in the figures of the drawings. All features described
or illustrated represent the present invention alone or in any
arbitrary combination, regardless of their recapitulation in the
patent claims or their back-reference, and regardless of their
wording in the description or illustration in the drawings.
Exemplary embodiments of the present invention are elucidated in
the following based on the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic block diagram of a radar system according to
an example embodiment of the present invention.
FIG. 2 illustrates an antenna array according to an example
embodiment of the present invention.
FIG. 3 illustrates an antenna array according to another example
embodiment of the present invention.
DETAILED DESCRIPTION
In FIG. 1 shows a radar system transceiver device 1 that includes a
monolithic microwave integrated circuit (MMIC) 2, which is an
integrated circuit including high-frequency circuit components that
process the signals in the microwave range or millimeter wave
range. Components of this type can, for example, involve frequency
splitters, frequency multipliers, mixers, amplifiers, or other
transmitting and receiving components. The output signal of an
oscillator 3 is fed to this monolithic microwave integrated circuit
2 as an input signal. This oscillator 3 generates a frequency
relayed as an output signal to the circuit elements connected
downstream and thus brings about the generation of a carrier
frequency of a microwave signal. Furthermore, a series of
transmitting antennas (Tx) 4, to which monolithic microwave
integrated circuit 2 outputs transmitted signals that are emitted
by transmitting antennas (Tx) 4, is connected to monolithic
microwave integrated circuit 2.
Furthermore, a series of receiving antennas (Rx) 5, which receive
microwave signals from the surroundings and feed them to circuit 2,
is connected to monolithic microwave integrated circuit 2. The
signals received by receiving antennas (Rx) 5 are preferably
signals which were previously emitted by transmitting antennas (Tx)
4 and partially reflected on the objects to be detected, and
converted back into electrical signals by receiving antennas (Rx)
5. The numbers of transmitting antennas (Tx) 4 and receiving
antennas (Rx) 5 do not have to be identical. It is conceivable, for
example, that a radar system 1 according to the present invention
includes a larger number of transmitting antennas 4 or a smaller
number of transmitting antennas 4 than the number of provided
receiving antennas 5. The received signals that are fed to
monolithic microwave integrated circuit 2 by receiving antennas 5
are processed in the MIMIC, and the output signals are fed to an
evaluating circuit 7 via MMIC output 6. It is conceivable, for
example, that mixers, demodulators, as well as analog/digital
converters are co-integrated on MIMIC 2 so that the received
signals are mixed down, demodulated, and digitally converted by
receiving antennas 5 on MMIC 2, and digitized object data are
relayed to evaluating circuit 7 via MIMIC output 6. It is, however,
also possible that only some of the listed components are
co-integrated on monolithic integrated circuit 2 and thus already
digitized data cannot be output at MIMIC output 6. In this case, it
is also possible to accommodate the analog/digital converter in
evaluating circuit 7 and to transfer an intermediate frequency
signal from MIMIC 2 via MMIC output 6. In evaluating circuit 7, the
signal reflections are evaluated with regard to their distance,
their azimuth, their elevation angle, as well as potentially also
with regard to their signal strength and fed to a further object
processing unit.
In the case of an adaptive distance control, the evaluation of the
azimuth of each of the particular detected objects is of great
importance, since it can be used to ascertain whether or not the
preceding vehicle is in one's own travel corridor.
In FIG. 2, a possible array of transmitting antennas (Tx) 4 as well
as of receiving antennas (Rx) 5 is illustrated, by use of which the
azimuth as well as the elevation angle of the preceding and
detected objects can be ascertained particularly advantageously.
For example, patch antennas 10, 11 illustrated in the lower half of
the image, as well as patch antennas 12 illustrated in the top left
corner are transmitting antennas (Tx) 4 which are provided for
transmitting. Patch antennas 14, 15, 16 as well as 19 are each
formed through 2-gap patch antennas and are each illustrated in the
top half of the image. In this case, the array is made up of N=3
transmitting antennas as well as n=1, i.e., exactly one vertically
offset transmitting antenna 12. In the illustrated example,
receiving antennas (Rx) 5 are made up of M=4 patch antennas and
m=1, i.e., exactly one vertically offset receiving antenna, as is
depicted by receiving antenna array 19. In the center between
illustrated antenna arrays 10 through 19, a possible location for
positioning monolithic microwave integrated circuit (MIMIC) 2 is
illustrated with the aid of a dashed line. It can be situated on
the back side of the high-frequency circuit board or on the front
side of the high-frequency circuit board on which antenna arrays 10
through 19 are applied. According to the present invention, the
front side of the high-frequency circuit board is understood to
mean the side of the circuit board on which the transmitting and
receiving antennas are situated. This embodiment has the advantage
that vias through the circuit board are dispensed with. Positioning
the MMIC(s) on the back side of the high-frequency circuit board
yields an advantages that there is greater latitude with regard to
the positioning of the MMIC, the MMIC has short connecting lines to
the other signal processing components, and the MIMIC can be better
protected, by an internal metal layer in the circuit board between
the front and the back sides of the high-frequency circuit board,
against interference radiation of incident electromagnetic signals.
In the case of this type of positioning of monolithic microwave
integrated circuit 2, approximately equally long feed lines between
the patch antennas and the MIMIC are obtained, which yields
advantages with regard to the phase position of the transmitted and
received signals and becomes noticeable in a minor attenuation of
the transmitted and received signals.
In particular antenna patches 10 through 19, particular phase
centers 8 are furthermore plotted which result for the sum of the
signals which are received or emitted by the particular antenna
patches. The horizontal array of transmitting antennas Tx or the
horizontal array of receiving antennas Rx makes it possible to
detect the azimuth of the objects to be detected. In this case, it
is not possible, however, to also ascertain the elevation angle of
reflection centers by using only horizontally situated antennas, so
that transmitting antenna 12 is vertically offset in relation to
the two other transmitting antennas 10 and 11 according to the
present invention and one, multiple or, optionally, all
transmitting antennas can simultaneously emit a transmitted signal.
The vertical offset of transmitting antenna 12 in relation to
antennas 10, 11 situated horizontally next to one another is in
this case offset `a` in the vertical direction in the specific
embodiment illustrated in FIG. 2. Likewise, receiving antennas 14
through 16 can be situated horizontally next to one another with
regard to their phase centers 8 in order to facilitate a good
determination of the azimuth of the objects to be detected.
Additional receiving antenna 19 is, in this case, offset by offset
`b` vertically to receiving antennas (Rx) 14 through 16 situated
horizontally next to one another, thus facilitating an
ascertainment of the elevation angle of the objects to be
detected.
Since the MIMO principle is also used in the elevation direction,
four measurements can be used. By offsetting transmitting antennas
Tx by a and by offsetting receiving antennas Rx by b, four virtual
positions 0; a; b; a+b result, so that a quality value can be
determined in each case for a 1-target as well as for a 2-target
elevation estimation.
A further exemplary embodiment of a radar system 1 according to the
present invention is shown in FIG. 3. This figure also shows
antenna arrays of patch antennas which are advantageously applied
on the top side of a high-frequency circuit board. It is also
conceivable that in the case of a particularly powerful radar
sensor, two MMICs can be cascaded, thus making available a larger
number of transmitting or receiving channels. It is conceivable,
for example, that four transmitting antennas (Tx) 10 through 12 as
well as eight receiving channels including receiving antennas (Rx)
14 through 21 are available. Here, it must be noted that the
transmitting and/or receiving channels are phase-synchronous only
within an MIMIC, but not necessarily between the two. It is thus
advantageous to carry out a coherent processing using the channels
of an MMIC. For example, the azimuth estimation can use the four
receiving channels of the first MMIC, while the four receiving
channels of the second MIMIC are used for the elevation angle
estimation. For a sensor system of this type, the array of the
patch antennas illustrated in FIG. 3 can be advantageously used. In
this case, the elevation angle is estimated without the MIMO
principle using four receiving antennas 18, 19, 20, 21 situated on
the right-hand side, so that an unambiguous elevation angle
estimation having a large aperture, i.e., having a high degree of
accuracy and a high degree of separability, can be implemented.
Since four measurements are used, it is possible to determine a
quality value for a 1-target as well as for a 2-target elevation
angle estimation in each case.
In this specific embodiment, the MIMO principle can additionally
also be used in the elevation direction in order to ascertain the
elevation angle of the object to be detected in an even improved
manner.
For this purpose, two transmitting antennas (Tx) 10 and 11 are
provided according to FIG. 3 which include a large number of patch
antennas and patch lines in each case and which are situated
horizontally next to one another in each case. Furthermore, two
further transmitting antennas (Tx) 12, 13, which are also shifted
only horizontally with regard to one another, are situated in the
lower area of FIG. 3. However, the phase centers of the two
transmitting antennas 10, 11 as well as of the two other
transmitting antennas 12, 13 are shifted vertically in relation to
one another, since these are shifted at distance a. This vertical
distance of the transmitting antennas is then used in addition to
the vertical offsets of receiving antennas 18, 19, 20, 21 for the
elevation angle estimation.
Furthermore, receiving antennas (Rx) are provided, receiving
antennas (Rx) 14, 15, 16, 17, 18 being in turn situated
horizontally next to one another and additional receiving antennas
(Rx) 19, 20, and 21 also being shifted vertically with regard to
their phase centers in relation to receiving antennas (Rx) 14
through 18 which are shifted horizontally. For example, receiving
antenna (Rx) 19 has a vertical offset b1 of the phase center;
receiving antenna 20, which is also shifted only vertically in
relation to vertically shifted receiving antenna 19, has an offset
b2 in relation to antennas 14 through 18 which are situated
horizontally next to one another; and a receiving antenna 21, which
is illustrated by way of example, has a vertical offset of the
phase center of b3 in relation to horizontally situated receiving
antennas 12 through 18. In the center of the illustrated
transmitting and receiving antennas 10 through 21, an area 2 is
illustrated in which the MIMIC, or in the case of two cascaded
MMICs, both MMICs, can be situated either on the back side or on
the front side of the circuit board carrying the antenna array,
since in this central area, the feed lines to the individual
transmitting and receiving antennas are approximately equally long
and thus a coherent emission of the transmitted signals and a
coherent processing of the received signals is made possible, since
the particular channels can be designed phase-synchronously to one
another.
The characteristics of the transmitting and/or receiving antennas
as well as of their exact positioning can be adapted to the
particular application, the vertical offsets of the transmitting
and receiving antennas being in particular also correspondingly
configured. For example, a front sensor can be implemented to have
a greater range and only one visual range by implementing a
vertically offset transmitting antenna as the focusing antenna. In
the case of applications of these sensors at the corners of a
vehicle, for example for blind spot monitoring or adjacent lane
monitoring functions, all transmitting antennas 10 through 13 and
all receiving antennas 14 through 21 can be implemented having a
wide emission characteristic.
* * * * *